Optical data medium containing; in the information layer, a dye as a light-absorbing compound

Abstract

Optical data medium containing in the information layer, a dye as a light-absorbing compound Abstract optical data medium containing a preferably transparent substrate which is optionally already coated with one or more barrier layers and on the surface of which an information layer which can be recorded on using light, optionally one or more barrier layers, and a cover layer containing a radiation-cured resin, have been applied, which data medium can he recorded on and read using focused blue light through the cover layer on the information layer, preferably laser light with the wavelength between 360 nm and 460 nm, the information layer containing a light-absorbing characterized in that at least one dye is used as the light-absorbing compound wherein the cover layer dies have a total thickness of 10 mum 177 m and the numerical aperture NA of the focusing objective lens setup is greater or equal 0.8.

Description

PRIOR ART[0001] The invention relates to a, preferably singly recordable, optical data medium which contains, in the information layer, at least one dye as a light-absorbing compound, and has a defined thickness of all the cover layers and can be recorded and readout with a focusing optical setup with a defined numerical aperture and a process for its production.[0002] The singly recordable optical data media using special light-absorbing substances or mixtures thereof are suitable in particular for use in the case of high-density recordable optical data media which operate with blue laser diodes, in particular GaN or SHG laser diodes (360-460 nm) and / or for use in the case of DVD-R or CD-R discs which operate with red (635-660 nm) or infrared (760-830 nm) laser diodes, and the application of the abovementioned dyes to a polymer substrate, made from for example polycarbonates, copolycarbonates, polycycloolefines, polyolefines, by spin-coating, vapour deposition or sputtering.[0003] ...

AI Technical Summary

Benefits of technology

The invention relates to a single-recordable optical data medium that uses dyes as light-absorbing compounds. The medium has a defined thickness and can be read and written with a focusing optical setup. The dyes absorb light in a specific wavelength range and can be applied to a polymer substrate using spin-coating, vapor deposition, or sputtering. The medium is suitable for high-density recordable optical data stores and can be designed for specific laser wavelengths. The invention provides suitable compounds that meet the requirements for use in the information layer of the medium, such as light stability, a good signal-to-noise ratio, and damage-free application to the substrate material.

Problems solved by technology

The amorphous layer of light-absorbing substances should preferably have a high heat distortion resistance, since otherwise further layers of organic or inorganic material which are applied by sputtering or vapour deposition to the light-absorbing information layer will form ill-defined interfaces through diffusion and thus adversely affect the reflectivity.

In addition, light-absorbing substances having too low a heat distortion resistance at the interface with a polymeric substrate can diffuse into the latter and once again adversely affect the reflectivity.

If a light-absorbing substance has a too high vapour pressure, said substance can sublime during the abovementioned sputtering or vapour deposition of further layers in a high vacuum and hence reduce the desired layer thickness.

This in turn leads to an adverse effect on the reflectivity.

Images